Atomizing nozzle assembly



Oct. 23, 1962 KARL-HEINZ HOHN 3,059,860

ATOMIZING NozzLE ASSEMBLY Filed Nov. 14, 1960 rates This inventionrelates to liquid spray apparatus, and, more specifically, to a nozzlearrangement for such apparatus in which a liquid is atomized by aninjector effect.

My improved nozzle assembly consists generally of a hollow or tubularair nozzle and a liquid nozzle arranged concentrically within said airnozzle. By the flow of air or other gaseous medium through the airnozzle, liquid is drawn through the liquid nozzle and is atomized andmixed with the air so that an evenly `distributed and highly atomizedspray is emitted by the nozzle arrangement.

My improved nozzle assembly is useful in spraying many dierent types ofliquids, such as paint, varnish and other finishes, disinfectants,insecticides and the like.

In apparatus of the kind heretofore known in the art, the air nozzle aswell as the liquid nozzle are generally attached by screw threads to theorifice of the apparatus. As already explained, the air flowing throughthe air nozzle generates a low or reduced pressure in front of theliquid nozzle. The value of the low or reduced pressure determines thedegree of atomization and is dependent, at least in part, on the size ofthe clearance, that is the annular space, between the liquid nozzle andthe air nozzle. In order to attain an even distribution and atomizationof the liquid, it is, therefore, important that exact concentricity bemaintained between the liquid nozzle and the air nozzle and that theannular space be of the same size around the entire periphery. Increasedaccuracy with respect to concentricity is required in the case ofnozzles of smaller diameter.

In the nozzle arrangements heretofore known exact co-axiality can beobtained only with considerable diiiiculty as the air nozzle and theliquid nozzle are separately threaded to the apparatus and it is almosstimpossible to make two screw threads exactly co-axial to each other asrequired for this purpose. Therefore, it is necessary to take steps tocenter the nozzles with respect to each other, and this is particularlytrue in the case of spray apparatus used for graphic purposes. Centeringin this fashion requires complicated devices which have to be operatedby skilled employees with the result that it can generally beaccomplished only in the factory in which the nozzle assembly isproduced. This means that the user encounters difficulties when thenozzles have to be disassembled and replaced, which is frequentlynecessary, for instance, if the nozzles are dirty or if a nozzle ofanother size is necessary. Under these circumstances, the apparatus hasto be sent to the factory for adjustment.

It is the main object of the present invention to overcome thedifficulties heretofore encountered and to provide a nozzle arrangementin which the nozzles are maintained in concentric relationship in asimple and improved manner and the liquid nozzle can be readilyexchanged and `replaced without affecting the centering of the liquidnozzle in relation to the air nozzle Other objects of the invention willbecome apparent when reading the following description in connectionwith the drawing, in which:

FIG. l is a longitudinal sectional view of one form of nozzlearrangement known in the prior art;

FIG. 2 is a cross-sectional View taken along line 2-2 of FIG. 1;

FIG. 3 is a longitudinal sectional view of one form of nozzlearrangement embodying the present invention;

FIG. 4 is a cross-sectional view in the direction of the arrows on theline 4 4 of FIG. 3;

latent ice FIG. 5 is a longitudinal sectional view of another form ofnozzle arrangement embodying the invention; and

FIG. 6 is a cross-sectional view in the direction of the arrows on theline 6-6 of FIG. 5.

In the known arrangement according to FIGS. 1 and 2 the body of theapparatus 1 is provided with an external thread 2 for connecting the airnozzle 3 and with an internal thread 4 for receiving the liquid nozzle5. Both threads 2 and 4 must be exactly co-axial in order to obtain anannular gap 6 between liquid nozzle 5 and an air nozzle 3 which is ofthe same size around its entire circumference. This can hardly beaccomplished because an exact co-axial manufacture of both threads inthe required precision without any tolerance is for all practicalpurposes, impossible. Therefore, it Igenerally happens that the liquidnozzle is eccentric with respect to the air nozzle and that the annularspace between the nozzles is smaller at one portion of the annulus thananother, as shown in FIG. 2. The cross-sectional area of gap 6 may bereduced to zero at a point of contact as shown, and this results inconsiderable difference in pressure reduction around the liquid nozzle 5with consequent uneven atomization of the liquid. The necessaryadjustment can be made only by skilled workmen with special tools and,generally speaking, the user is unable to make these adjustments.

The present invention overcomes these diiculties in that the liquidnozzle is not fixed to the apparatus but is in guided engagement withthe air nozzles so that a concentric relationship is maintained at alltimes and the liquid nozzle may be readily exchanged or replaced withrelatively non-skilled personnel as no adjustment of the parts isthereafter necessary.

In the embodiment shown in FIGS. 3 and 4, the air nozzle 13 is, as inFIG. l, screwed to the body 11 by thread 12. The inner surface 17 of theair nozzle is conical in shape and the :liquid nozzle 15 is in contactwith the conical surface along a plurality of contact lines Ztl. TheContact lines are preferably evenly spaced and are preferably at leastthree in number and they form mantel or envelope lines of a cone havingthe same apex angle as the conical inner surface of the air nozzle.Thus, the liquid nozzle centers itself completely and automatically andis pressed against the supply line 18 when the air nozzle is screwed tothe thread 12. A sealing ring 19 is preferably interposed between theliquid nozzle and the ysupply line 18 to insure sealing engagementbetween these parts. Air passageways 21 of uniform cross-sectional sizeand area are formed between the contact lines 10 and serve as passagesfor distributing the air.

In the assembly shown in FIGS. 3 and 4, air enters the air nozzle fromthe apparatus through channel 22 which is connected to a source of airunder pressure and liquid enters the nozzle from the apparatus throughchannel 18. Due to the fact that the air passageways or cavities Z1between the nozzles are of uniform, crosssectional area, the air isevenly distributed around the outer end of the liquid nozzle 15 with theresult that there will be uniform reduction in pressure and uniformatomization of the liquid from the liquid nozzle.

Naturally, it is possible to use point contact rather than line contactbetween the liquid nozzle and air nozzle in order to obtainconcentricity and, under those circumstances, the contact point should-be arranged along lines on a projected conical envelope for the nozzle.It is likewise po-ssible to make the external surface of the liquidnozzle in the form of a complete cone mantel or envelope and to providethe contact lines or points on the internal surface of the air nozzle.

In the embodiment shown in FIGS. 5 and 6, the liquid nozzle 35 is guidedin a separate cylindrical member 32 which is inserted into the airnozzle 13. The air nozzle 13 is attached to the apparatus by threads 12.For this purpose, the liquid nozzle 35 is provided with a cylindricalportion 23, the outer diameter of which corresponds to the innerdiameter of cylindrical member 32 and has a sliding fit therewith. Themember 32 abuts against a shoulder 24 of the liquid nozzle 35 and urgesit against the supply line 18 when the air nozzle i3 is screwed onto thethread 12. Channels 36 are provided in the member 32 for passage of theatomizing air. Thus, the cylindrical spacer or collar 32 has engagementwith the inner surface of the air nozzle at a plurality of preferablyuniformly spaced areas around the periphery thereof and has contactingengagement with the entire periphery of the liquid nozzle 13, therebyserving to hold the nozzles in exactly concentric relationship.

The embodiment of FIGS. 5 and 6 can more easily be manufactured than thearrangement of FIGS. 3 and 4. Although there is no self-adjustment, theouter diameter of liquid nozzle 35 and the inner diameter of spacermember 32 can be made with such accuracy that substantial concentricityof the nozzles is obtained.

In the arrangement shown in FIGS. 5 and 6, spacer member 32 is shown asa separate unit, but it should be understood that it may be formedintegrally with one of the parts, such as the liquid nozzle 35. Underthose circumstances, the outer face of the liquid nozzle would contactdirectly against the inner face of the air nozzle. In this connection,as previously pointed out, it is sufficient to have contact at aplurality of points or lines lying along at least three envelope ormantel lines, thereby insuring a co-axial relationship. In thearrangement shown in FIGS. 5 and 6, it will thus be `seen that theliquid and air nozzles are held in co-axial relationship, and that theliquid nozzle may be readily replaced and exchanged without the need ofspecial tools or skilled personnel.

In both forms of my apparatus, shown in FIGS. 3 and 4 and FIGS. 5 and 6,respectively, the nozzles are maintained in concentric relationship byspacing or guiding means providing engagement at a plurality ofcircumferentially spaced portions between the liquid nozzle and theinner surface of the air or gas nozzle. The discharge end of the liquidnozzle is free from obstruction around the outer surface thereof and theair enter-ing through supply line 22 and the air nozzle would beuniformly distributed around the end of the liquid nozzle and there willbe a uniform reduction in pressure.

Modifications may be made in the illustrated and described embodimentsof my invention without departing from the invention as set forth in theaccompanying claims.

I claim:

1. An atomizing nozzle assembly having concentrically arranged liquidand air nozzles adapted for detachable connection to an externallythreaded mounting having a front face with liquid and air supplychannels comprising a tubular air nozzle having an inner surface whichis circular in cross-section for substantially its entire length andformed with a discharge outlet at its forward end and an internallythreaded flange -at its opposite end for detachable connection yto themounting with the interior of the nozzle in communication with the airsupply channel in the face thereof, a tubular liquid nozzle shorter inlength than the air nozzle and disposed wholly inside the air nozzlewith a discharge outlet at its forward end spaced inwardly from thedischarge outlet of the air nozzle and with a sealing surface at itsopposite end spaced inwardly from the attaching flange of the air nozzleand cooperable to seal against and having abutting engagement only withthe face of the mounting in communication with the liquid supply channelwhen the attaching flange is attached to the mounting and guiding meansbetween the liquid and air nozzles spaced inwardly from the dischargeend of the nozzles and having at least three circumferentially spacedrelatively elongated longitudinally extending guiding means engaging theinner surface of the air nozzle for substantially their entire lengthand shaped and arranged to conform with the envelope shane of the innersurface of the air nozzle, said liquid nozzle being free from directconnection with said mounting and having only said abutting engagementwith the face thereof so that the liquid nozzle is held in fixedconcentric position with respect to said air nozzle solely by saidlongitudinally extending guiding means.

2. An atomizing nozzle assembly having concentrically arranged liquidand air nozzles adapted for detachable connection to an externallythreaded mounting having a face with liquid and air supply channelstherein as set forth in claim 1 in which the inner surface of thetubular air nozzle is conical in shape and the circumferentially spaced,relatively elongated, longitudinally extending guiding means are in theform of conical envelope lines having the same apex angle as the innersurface of the air nozzle.

3. An atomizing nozzle assembly having concentrically arranged liquidand air nozzles adapted for detachable connection to an externallythreaded mounting having a face with liquid and air supply channelstherein as set forth in claim l in which the guiding means consists of aseparate member fitted tightly between the air and liquid nozzles.

4. An atomizing nozzle assembly having concentrically arranged liquidand air nozzles adapted for detachable connection to an externallythreaded mounting having a face with liquid and air supply channelstherein as set forth in claim l in which a sealing annulus is providedbetween the sealing surface of the liquid nozzle and the front face ofthe mounting.

References Cited in the tile of this patent UNITED STATES PATENTS918,754 Lederer Apr. 20, 1909 1,762,552 Gradolph June 10, 1930 2,034,660Lohse Mar. 17, 1936 2,895,685 Peeps July 2l, 1959 2,965,309 Parrott Dec.20, 1960

